The Harry Hamster has everything in that is needed. Rather than add anything to it (this might upset the proportions of nutrients) it would be better to give the extras separetely. So I have a food dish for the hamster mix and another dish somewhere else in the cage (keeps them active going from one dish to another!) which I put his piece of daily veg on and a few Linseeds. He then gets an extra daily on top of a little hide (he knows where to look for it) maybe half a walnut or a small piece of apple eg. Then I scatter something extra occasionally - eg a few pumpkin seeds or sunflower seeds. That isn’t necessary but they like foraging for them
You don’t need additional pellets - hust the odd healthy treat, a chew stick (I like the rosewood naturals ones) and a very small piece of fresh veg each day (every 3 days at first till they get used to it).